1. Field
This invention relates to carbonylation reactions of an alcohol, ether, ester, and halide derivative thereof with carbon monoxide to form carboxylic acids and esters.
2. Description of the Prior Art
Carbonylation processes for the preparation of carboxylic acids and esters from a variety of reactants are well known in the art. One of the better known carbonylation processes involves the synthesis of acetic acid by the reaction of methanol and carbon monoxide in the presence of a catalyst. Various catalyst systems have been reported as being effective for carbonylation processes, but each has had certain disadvantages, for example, instability of the catalyst, lack of product selectivity, low levels of catalyst reactivity, or loss of highly volatile catalyst from the reaction. Particular processes are shown in the following U.S. patents:
U.S. Pat. No. 3,530,168 shows a process for forming carboxylic acid esters by contacting an olefin, carbon monoxide and oxygen with a catalyst comprising a Group VIII noble metal, e.g., palladium complexed with a biphyllic phosphine or arsine ligand, i.e., those having an element with a pair of electrons capable of forming a coordinate bond with a metal atom and simultaneously having the ability to accept electrons from the metal of the catalyst.
U.S. Pat. No. 3,689,533 discloses a process for preparing carboxylic acids and esters by reacting an alcohol and carbon monoxide in the presence of a catalyst comprising the decomposition product of rhodium nitrate and a halogen component.
U.S. Pat. No. 3,769,326 discloses a process for preparing aromatic carboxylic acids and esters by reacting an aromatic alcohol, ester, ether and halide derivative thereof with carbon monoxide in the presence of a catalyst consisting essentially of a rhodium component and a halogen component. Monodentate phosphine and arsine ligands are the only ligands shown.
U.S. Pat. No. 3,887,595 discloses a process for carbonylating olefinic unsaturated hydrocarbons to form acids, esters and acid anhydrides by catalyzing the reaction with a zero valent palladium or platinum complex stabilized with a phosphine ligand.
U.S. Pat. No. 3,917,670 discloses a process for the carbonylation of organomercurials to form carboxylic acids. In that carbonylation process, a catalyst comprising palladium complexed with a phosphine ligand is employed.
U.S. Pat. No. 3,917,677 discloses a process for preparing carboxylic acid esters by reacting an ethylenically unsaturated compound, e.g., propylene, with carbon monoxide and an alcohol in the presence of a catalyst consisting essentially of a rhodium component and a tertiary organophosphorous compound free of halogen.
U.S. Pat. No. 3,923,880 discloses a process for carbonylating alcohol and alcohol derivatives to form carboxylic acids using a catalyst complex containing cations of rhodium or iridium and an anionic moiety other than halide, e.g., tetraaryl borate, phosphate, sulphate, perchlorates, iodates and bromates.
Brodzki et al. in an article appearing in 61 Bull. Chim. Soc. Fr., 61-65 (1976) entitled "Catalytic Properties of Complexes of Precious Metals: Carbonylation of Methanol to Acetic Acid by Rhodium Compounds" discloses the carbonylation of methanol to acetic acid in the presence of a rhodium complex promoted with methyl iodide. The authors conducted the carbonylation with both monodentate and polydentate chelating phosphine ligands, and the conclusion of the authors was that the bidentate ligand is inactive.